/diy/ - Do It Yourself

[Anonymous No.710533]

Hey /diy/, what do?

[Anonymous No.710534]

>>710533
shits broke. take it in to a shop. ask about used parts, and where to get them, maybe a co-op is out there nearby. they can show you everything you need to know and are generally pretty chill cool guiz

[Anonymous No.710538]

>>710533
fix it.

[Anonymous No.710539]

take it back to walmart

[Anonymous No.710540]

>>710539
It's not a new bike lol, just wear and tear, but I was hoping somebody knew how to reattach it

[Anonymous No.710559]

Take it to a shop, best thing to do. And ask them to check the other side, they can be lose from the start, I know, I am a bike repair man.

[Anonymous No.710562]

>>710533
Time for a replacement crankset.

[Anonymous No.710586]

Op here, I just got home and decided to check it out. Turns out there's a nut inside the crankshaft that must've come loose, so I popped it out, put the shaft back on and tightened it up. Thanks for the suggestions though.

[Julez No.710588]

Hey mate,

you got a cone bearing.

http://www.radforum.de/threads/174557-was-ist-das-fuer-ein-tretlager

The ring with the slots is a locking nut having the same thread as the frame. The barely visible thread on the cone, the part in the middle with the width flat, should indicate which direction to turn to get it loose. The part on the other side may turn in the opposite direction. You probably need to get the crank assembly off before being able to reach it. Take it to your dealer and demand a new one. But this part is very outdated and hardly used any more, and least not in Germany. Well, the new part screws in first on the chain side nice and tight. Then you screw in the cone on the other side, and adjust it until the bearing begins to move with a tiny bit of resistance. Then you lock it in place tightening the locknut, and reassemble the crankarms.

Google "fatigue failure" and have a look at the broken part, maybe it's the same.

[Julez No.710589]

Oh great, I crafted my response under the impression that the threaded pard was largely broken off with only a stub remaining. Ah well, better this way than having to tear everything apart.

[Anonymous No.711321]

>>710586
>Op here, I just got home and decided to check it out. Turns out there's a nut inside the crankshaft that must've come loose, so I popped it out, put the shaft back on and tightened it up. Thanks for the suggestions though.
I am not a professional bike guy, but anyway---
the times I have had this happen (or seen it happen to others) the cranks were ruined and needed to be replaced.

The reason is because the cranks are aluminum and the bottom bracket spindle is steel. The square hole in the crank has to fit *perfectly* on the bottom bracket spindle, or the crank will keep flexing on the spindle and causing the nut holding the crank on to come loose. And you can't fix the damaged hole in the crank, so you had to buy new cranks.

I don't blame you for trying to keep using it, you might get lucky. Thread locking compound might help. But its probably not going to work.

If you want to find new cranks, what you need is "square-taper" MTB cranks. There's a few for $30 on ebay.

[Anonymous No.711337]

>>711321
I dont know, cranks are pretty durable. it seems like his just fell off. I couldnt even get mine all the way down the taper with 800nm of force. I'm sure there's still some grip left there. not to mention bikes have these crafty toothed bolts for everything. I fear for my life when I ride my e-bike. bicycle wheels are held on so shittily yet still work.

[Anonymous No.711338]

>>710586
also OP, make sure you tighten that bolt properly when you put it on. the crank shouldnt be able to slip off even with the locking bolt off.

[Anonymous No.711340]

>>711337
yeah, but the problem is no matter how tight you do the center nut, the cranks will flop around on the hub, imparting rotational forces onto the nut, loostening it, which allows more movement, which increases the crank wear etc. this is prolly how op lost the nut in the first place. i would be getting new crank arms.

[Anonymous No.711396]

>>710588
>one bearing
>hardly used any more
wat

Seriously, those things are gone? What about in wheel hubs?

They were always an enormous pain in the ass to get adjusted properly. It's been years since I've worked on bicycles.

[Anonymous No.711409]

>>711338
>also OP, make sure you tighten that bolt properly when you put it on. the crank shouldnt be able to slip off even with the locking bolt off.
the problem is that when the nut got loose the first time, the square hole in the aluminum crank got chewed up, and no longer fits properly
and if it doesn't fit tight and stay still on the spindle, it will loosen the nut no matter how tight the nut is

[Anonymous No.711464]

[Anonymous No.711728]

>>711409
Ex bike store manager here, you are a fucking retard. Op, loosen it off, and put a drop of loctite on the threads before retightening. Won't come loose again.

[Anonymous No.711731]

>>711728
> Expecting loctite to hold one of the most stressed parts/nuts on the bike.
> Ex bike store manager.
I can understand why.

[Anonymous No.711735]

>>711731
It's not out of square you fucknard, it's not an aluminum crank arm, it's steel. Fgt. Lrn2bike.

[Anonymous No.711799]

>>711735
Steel cranks are always of softer composition compared to axle. They have to be that way to jam on the axle. This means they too can be damaged when used loose, only slower.

If they have not been ridden for to long that way, it might be that the damage is small and tightening the crank really hard would shape it right.

I've had this happen several times. Alu cranks where always dud or had to be reworked, steel sometimes didn't come loose afterwards.

You can use Loctite, but usually when it works it's only because the crank hasn't been actually damaged yet. Otherwise the crank would start to wiggle again, just without undoing the nut.

[Anonymous No.711805]

>>711799
> Alu cranks where always dud or had to be reworked.
See >>711735
> steel sometimes didn't come loose afterwards.
Which one is it? sometimes? or didn't?
> You can use Loctite, but usually when it works it's only because the crank hasn't been actually damaged yet.

See >>710533
Look at the bike Fagtron.
It's a cheapass piece of shit. shit-tier brakes, Sprockets, Crank, Suspension, Stand, Generic steel single walled rims with equally shitty steel spokes.

The crank still has the sticker on it and has not been rubbed off, means that it has barely been ridden. not correctly tightened from factory

Ex bike store manager, once again responding to dumbasses.

I swear I'm surrounded by fucking idiots on this post.

[Anonymous No.711817]

>>711805
>Ex
No wonder... All that hate and anger just to dismiss every other advice because muh Locklite.

[Anonymous No.711827]

>>711731
Mechanic of 8 years here. I use loctite on high torsion bolts all the time. If you use decent stuff and apply it correctly, then the only way to get a bolt off is to heat it up with blowtorch to destroy the loctite.

[Anonymous No.711843]

>>711827
Saw a dude use loctite on a lathe to hold a tiny part on a mandrel.

[Julez No.711902]

Well, I had once tried to get my crank arms of the bearing, but failed due to not having a pulling tool. I forgot to put the bolt back in. Over time, it got worked loose, and finally fell of. So my arm experienced practically the same as OP. I put it back on, tightened the bolt properly, and rode that bike for 15 years without problems. So, an arm becoming loose and falling off does not need neccessarily that it gets destroyed in that process. Before messing around otherwise, I would put a piece of scotch tape over the nut to prevent it from falling off and getting lost. After every ride, I would briefly check if the nut is still as tight as before the ride. Also, take the wrench with you in case you feel that it becomes loose during the ride. If it did not become loose during the next 50km or so, it is safe to assume that the crank arm did not get damaged somehow, and will sit firmly in it's position in the future. I would still remove the nut and assemble it again with loctite just to be sure.

[Anonymous No.712246]

>>711817
See
>>711827
>>711843
>>711902
Fgt. Like i said, Lrn2Bike.